// 异常

main () {
  try {
    throw FormatException('Expected at least 1 section');
  } on FormatException {
    // 一个特殊的异常
  } on Exception catch (e) {
    // 其他任何异常
    print('Unknown exception: $e');
  } catch (e) {
    // 没有指定的类型，处理所有异常
    print('Something really unknown: $e');
    rethrow; // Allow callers to see the exception.
  } finally {
    // Always clean up, even if an exception is thrown.s
  }
}